The present invention relates to a process for preparing granular potassium sorbate.
In general, potassium sorbate is prepared by reacting sorbic acid with potassium hydroxide or a potassium salt such as potassium carbonate in a medium of water or an organic solvent, and then recovered from the reaction mixture by means of recrystallization, spray drying or drum drying. The thus prepared potassium sorbate is obtained in a form of crystalline powder.
Potassium sorbate has excellent antifungal activity and nontoxicity, and has been effectively employed as a preservative for foods such as a fish-paste product or cheese. However, when a powder of potassium sorbate is employed in such a use, workability is not so good compared with granule. For instance, the fine powder is easy to scatter in handling. Also, when the powder is dissolved in water, it remains floated on the surface and does not dissolve quickly.
For the purpose of solving such problems, it has been proposed to granulate the powdery potassium sorbate. As a preferred granule, it is required to be so rigid that the granule is not broken even under load or friction during transportation, and to have good solubility in water. Also, it is desirable that the granule does not contain a binder because of lowering the quality of the granule, and that the granule is prepared in high yield.
As a practical process, a process for preparing granular potassium sorbate by wetting powders of potassium sorbate with water or an organic solvent and applying it to a granulator such as vibration type or extrusion type is proposed. For instance, there is disclosed in U.S. Pat. No. 3,758,563 a process for producing granular potassium sorbate by wetting powdery potassium sorbate with water or a mixture of water and an organic solvent, molding it with particular types of extruding granulators and drying it. According to the process, however, particular types of extruding granulators wherein not only extruding force but also lateral stress are applied to the wetted powder must be employed.